1. A movie made with a low or limited budget.
2. The phrase is more commonly misused to describe a movie of noticably poor quality.
3. It is rarely used to describe a movie with a low profit margin regardless of budget size, but I have heard it used this way occasionally.

1. "For a b movie, it had some pretty sweet visual effects."
2. "That might have been the worst movie I have ever seen. I wish the reviewer had mentioned it was a b movie"

The term "B-movie" was used to distinguish a film from an "A=movie", in a time before TV when movies were all there were. Movies were cranked out continually, the way TV shows are now. An A-movie is a high-budget, highly promoted feature film. A B-movie is the regular, lower budget stuff.

A movie without the benefit of well-recognised actors and cinema screenings, though also commonly associated with poor acting, bad effects and a minimal or ridiculous storyline which justifies any number of violent acts or scantily clad women.

More often than not these films can be enjoyed with a group of friends armed with large quantities of alcohol and be found more entertaining than anything with enough budget to make blood not look like strawberry toothpaste.

Can also be connected to an 'A-movie' with a cult following or all the qualities listed above.

Brain dead is a B movie.

Anything directed by Alex Chandon is a B movie (or soft porn).

Alien resurrection has more plot holes than Stars Wars episode III and is more unnecessary than episodes I, II and III - and therefore should be a B movie.